Arocket was launched into the air from a platform above the ground. the height, in feet, of the rocket above the ground t seconds after being thrown can be determined by the expression -16t^2+64t+80. what does the 80 in the expression represent?

Assume that there is a 11% rate of disk drive failure in a year. a. if all your computer data is stored on a hard disk drive with a copy stored on a second hard disk drive, what is the probability that during a year, you can avoid catastrophe with at least one working drive? b. if copies of all your computer data are stored on four independent hard disk drives, what is the probability that during a year, you can avoid catastrophe with at least one working drive?